Suture (geology)

In structural geology, a suture is a joining together along a major fault zone, of separate terranes, tectonic units that have different plate tectonic, metamorphic and paleogeographic histories. The suture is often represented on the surface by an orogen or mountain range. The term was borrowed from surgery where it describes the sewing together of two pieces of tissue, but the sutures of the skull, where separate plates of bone have fused, may be a better metaphor.

In plate tectonics, sutures are seen as the remains of subduction zones, and the terranes that are joined together are interpreted as fragments of different paleocontinents or tectonic plates.

Outcrops of sutures can vary in width from a few hundred meters to a couple of kilometers. They can be networks of mylonitic shear zones or brittle fault zones, but are usually both. Sutures are usually associated with igneous intrusions and tectonic lenses with varying kinds of lithologies from plutonic rocks to ophiolitic fragments.

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